Keith
I believe that your THC sample rate will determen how fast it can react to a voltage change. Too Slow and it caps teh speed of teh Z early ??
(;-) TP
Electronics and computers can be super fast and assuming that is so, then the real limiting factor is mechanical, so let's have a think about this:
My theory is that the maximum USEABLE rate of a THC is completely determined by how fast a Z-axis can change direction then change back again. If you had a THC sample rate of say 50 times/sec then the worst case scenario is for 1/50 second the Z is being told to go up then for the next 1/50 second the Z is being told to go down. How many Z axis are capable of taking advantage of such demands.
I can easily bump up my sample rate to 100/sec and that's still giving me 10 milliseconds per sample to do all the calculations, compare with SET VOLTS, etc and give a THC UP/DOWN signal, certainly doable with my microcontroller.
BUT is there any benefit to reacting in 1/100th second when I can't see a Z axis being mechanically capable of taking advantage of that speed. I heard that a humming birds wings flap at about 50 times a second and when I see those little guys I can't imagine a Z axis competing with them.
And how long would be considered too long to wait for a THC UP/DOWN signal when the volts had gone outside of the SET VOLTS deadband range. My reasoning for NOT wanting to sample at such a high rate is that I can sample the voltage for longer periods and get better averaging of the noisy spiky plasma voltage.
Do you see my reasoning ?
Keith.